Answer:
a) 52.2 J
b) 48.77 m/s
Explanation:
a)47 g = 0.047 jg
The kinetic (and total mechanical energy) of the ball at the ground is
[tex]E = mv^2/2 = 63.544 J[/tex]
The potential energy of the ball at its highest point 24.6m is. Let g = 9.8m/s2
[tex]E_h = mgh = 0.047*9.8*24.6 = 11.33 J[/tex]
Since the potential energy at the highest height is less than the total mechanical energy on ground, the difference must be kinetic energy
[tex]E_k = E - E_h = 63.544 - 11.33 = 52.2J[/tex]
b) 8m below 24.6m is 16.6m. The potential energy at this point is
[tex]E_{p8} = mgh = 0.047*9.8*16.6 = 7.64 J[/tex]
And so the kinetic energy at this point is
[tex]E_{k8} = E - E_{p8} = 63.544 - 7.64 = 55.9 J[/tex]
So the speed is
[tex]mv^2/2 = 55.9[/tex]
[tex]v^2 = 2*55.9/0.047 = 2378.64[/tex]
[tex]v = \sqrt{2378.64} = 48.77 m/s[/tex]
